Gas turbine engines generally include a turbine section downstream of a combustion section that is rotatable with a compressor section to operate the gas turbine engine to generate power, such as propulsive thrust. General gas turbine engine design criteria often include conflicting criteria that must be balanced or compromised, including increasing fuel efficiency, operational efficiency, and/or power output while maintaining or reducing weight, part count, and/or packaging (i.e. axial and/or radial dimensions of the engine).
Known interdigitated gas turbine engines (i.e., alternating rows along an axial length of one rotor assembly and another) are limited in longitudinal dimensions, and thus, interdigitation with another turbine rotor that may otherwise increase efficiency or power output is restricted by rotor dynamics, leakages, and other inefficiencies. For example, efficiencies gained by interdigitation may be offset by inefficiencies due to increased gaps at seal interfaces, such as between turbine blades and surrounding shrouds. Increased unsupported turbine axial length due to interdigitation may generally increase leakages across seal interfaces as well as adversely affect rotor dynamics (e.g., vibrations and balance) and/or structural life of the turbine rotors.
Therefore, there is a need for structures that may reduce seal interface clearances, enable further interdigitation of turbine rotors along the engine length, decrease unsupported turbine length, and generally improve gas turbine engine efficiency.